SGA is not much of a threshold fandom; for the most part, slash fans seem to have come to SGA from other existing slash fandoms. It has been called an "old school slash" fandom, possibly because of the lack of ironic distance in its approach to slash. It is also possible that the subject matter and types of stories being written were a part of the reason, rather than simply the 'tone' of the fandom. It might even have been something that happened due in part to Fannish Drift.

Origins of McKay/Sheppard Fans and Fannish Drift

Since SGA was a spin-off of a pre-existing show, there was already a large fan base interested in the Stargate universe. At around the same time, many Enterprise fans were growing disenchanted with their show, and decided to try Stargate Atlantis. These two communities brought with them an interest in canon-centered, character-based stories, akin to classic first and second wave slash stories. [1]

The pre-existing Stargate community existed primarily on mailing lists, and was supported by the Area 52 archive. Other SGA-focused mailing lists were created, paralleling the existing SG-1 ones, and Area 52 opened up to SGA fan fiction. On the Enterprise fan side, the need for a more-SGA focused archive was clear, and so the Wraithbait archive was formed along with its associated mailing lists. The interesting thing here is that the Enterprise crew also brought with them a strong interest in Sheppard/Weir and threesomes with their McKay/Sheppard slash, while the SG-1 community seems to have been more exclusively slash-focused.

Both sets of communities had some people who were also set up in LJ and some who posted to Fanfiction.net, so all major slash community hubs were hit with fiction right away, exposing large swaths of potential new fans to the show. In-person pimping at the Escapade 2005 slash con also exposed a lot of existing slash fans to the possibilities inherent in the show, and the relationship between John and Rodney. However, the first ship_manifesto posted was Sheppard/Weir, and the first slash one Beckett/McKay; both were posted in the late November/early December timeframe in 2004. The John/Rodney manifesto[2] wasn't posted until second season started, July 2005. Crack Van's brief introduction to the show [3] was posted at the end of February, 2005.

The next two big groups to populate the Stargate Atlantis slash community were Popslash writers and writers from Smallville. Popslash was also in very early; on crack_van, the first popslash/SGA crossover recommendation is "Untitled by Coreopsis", recommended on Dec 15, 2005 [4] The rec even includes pictures as the two communities may not have been familiar to each other. As evidenced by Singular Tropes By Fandom, the popslash writers were noted for writing fantastical stories without requiring a lot of explanation; Smallville had its fantastical element stories as well, and with the addition of a few Harry Potter slash fans, this set the stage for the crackfic vs. canon-based fic controversy that keeps popping up in the McKay/Sheppard fandom. The fantastical also typifies Lezlie's third wave of slash.[1]

RPS fans such as LOTRPS writers acted as the next wave, bringing with them a much more realistic tone, which also rather nicely aligns with Lezlie's fourth wave, fascinating, given that the original theory was written in 1993. As general steps, the fandom passed through the wave progression in a classical manner; perhaps this is part of why the McKay/Sheppard slash fandom is considered "old school slash," despite its high percentage of crackfic.

Everything that SGA touches, turns into AU SGA Crack....She introduced us to the show when we were just innocent, naive waifs and occasional fans and appreciators of SG-1. She pushed and pushed and pushed SGA on us until we sighed mightily, crossed our arms and flopped on the couch and were slowly drawn into a fandom where psychic telepathic whales are canon. - artemisiabrisol, Welcome to McShep Tin Hat Nation, 21 October 2008, (accessed October 22, 2008)

Two Weeks by The Grrrl and mmmchelle -- Important early look at John and his parents, and what it would be like to vacation on Earth after being in another galaxy. (2/2005)

Transcendental by astolat -- v. early novel. Controversial in that Rodney shows himself able to repeatedly think Sheppard under a table. Some felt John was humiliated by Rodney; others adored the novel. (3/2005)

elderwitty compiled the Giant McShep AU List, which includes hundreds (as of March 2011 close to 900) of stories featuring such alternate universe roles as Actor/Agent, Figure Skater/Coach,Lumberjack/Environmentalist, Model/Painter, Nursery school teacher/Clown, Singer/Keyboard player, Sith/Jedi and TV Producer/Talk Show Host.